This disclosure relates to a method for repairing a worn surface of a gas turbine engine component.
Gas turbine engines typically include a compressor section, a combustor section and a turbine section. Air is pressurized in the compressor section, and is mixed with fuel and burned in the combustor section to energize and expand the air and accelerate the airflow into the turbine section. The hot combustion gases that exit the combustor section flow downstream through the turbine section, which extracts kinetic energy from the expanding gases and converts the energy into mechanical power to drive the compressor section.
The compressor section of the gas turbine engine typically includes multiple compression stages to obtain high pressure levels. Each compressor stage consists of alternating rows of stator assemblies that include stationary airfoils called stator vanes followed by rotor assemblies including moving airfoils called rotor blades. The stator vanes direct incoming airflow to the next set of rotor blades.
During operation, portions of the stator assemblies may become worn as a result of rubbing that occurs between the stator assemblies and surrounding components of the gas turbine engine. The rubbing may wear and stress portions of the stator assemblies.
Replacing an entire stator assembly is expensive due to material and machining costs. Accordingly, stator assemblies are often repaired instead of replaced. The repairs generally involve removing the worn surfaces of the stator assembly, and then restoring them with weld filler or similar material on a surface of the component. The material build-up is machined to an appropriate shape to form a restored surface.
A known gas tungsten arc (GTA) welding process is generally used to repair worn surfaces of gas turbine engine components. The GTA welding process may be performed manually or robotically to deposit weld material on a worn area of the component. However, GTA welding is a relatively slow build-up process that, because of the inherent heat input, can cause unacceptable component distortion. These aspects have prompted the aerospace industry to seek faster and less heat intensive welding processes.